1. Field of the Invention
The invention relates an orthogonal frequency division multiplexing (OFDM) technology, and particularly relates to a method of data allocation, a wireless transmitting apparatus using the same, a signal receiving method and a wireless receiving apparatus using the same based on the OFDM technology.
2. Description of Related Art
Owing to advantages such as having a better efficiency of the frequency spectrum, effectively coping with multipath channel, and having a high data transmission speed, the orthogonal frequency division modulation technology has been broadly used in relevant fields of communication such as digital television broadcasting, accessing the Internet of digital subscriber lines (DSL), and 4G mobile communication networks, etc.
FIG. 1 shows a conventional dual branch orthogonal frequency division multiplexing receiving device. Referring to FIG. 1, it is assumed that a receiving device 100 has two antenna units 111 and corresponding receivers 110 and 120. The following descriptions are based on the antenna unit 111 and the corresponding receiver 110. After being received by using the antenna unit 110, a radio frequency signal (Z1(t)) is divided into two paths, i.e., an in-phase path (I-path) 150 and a quadrature-phase path (Q-path) 155.
In the in-phase path 150, the frequency mixer 112 performs a mixing process (i.e., multiplying ILO1(t)=cos(2πfct) by using a multiplier) based on a carrier frequency fc generated by an oscillation generator 113, and the signal is processed by a low pass filter (LPF) 116 and an analog-to-digital converter 118, so as to generate a baseband signal (IBB1(t)) of the in-phase path 150. Besides, in the quadrature-phase path 155, a mixer 114 performs a mixing process based on the carrier frequency fc generated by the oscillation generator 113 and rotates the phase 90°+θ1, then the signal is processed by an amplifier 115 with a gain g1 (i.e., multiplying QLO1(t)=−g1 sin(2πfct+θ1) by using a multiplier) and processed by a low pass filter 117 and a analog-to-digital converter 119, so as to generate a baseband signal (QBB1(t)) of the quadrature-path 155. Then, the baseband signals (IBB1(t) and QBB(t)) are transmitted to a signal processing module 170 (e.g., a long term evolution (LTE) modem).
However, since the in-phase path and the quadrature-phase path are both present, the dual branch orthogonal frequency division multiplexing receiver usually faces an in-phase/quadrature-phase imbalance.